The invention relates to biologic vertebral reconstruction and, more particularly, to devices and methods for biologic vertebral reconstruction utilizing a biologically active jacket inserted into a cavity formed in a vertebra to be reconstructed.
Vertebral compression fractures are quite common in the elderly population. These fractures occur following minor injuries or spontaneously in the elderly osteoporotic spine. The other group of patients, usually middle aged, is those on long term steroid therapy for conditions such as chronic obstructive pulmonary disease. In the younger population with normal bone mineralization, vertebral fractures usually occur following high energy injuries such as motor vehicle accidents or a fall from heights.
Until recently, the elderly osteoporotic fractures were treated with pain control and bracing, depending on the severity of pain. However, over the last decade, there has been increasing use of minimally invasive procedures such as vertebroplasty and Kyphoplasty, whereby bone cement in a state of low viscosity is injected into the fractured vertebrae. As the bone cement sets it glues together the fragments of the fractured vertebra. Patients usually wake up from anesthesia with minimal discomfort.
As the use of this technique became more common, some adverse effects of the treatment have become apparent. At the time of surgery, patients may suffer from cardio-respiratory failure associated from infusion of large amounts of polymethylmethacrylate monomers into the circulation; in the case of vertebroplasty which requires injection of the cement at high pressures, extrusion of the cement into the venous channels and embolization into the pulmonary veins have been described; the cement may extrude through the cracks in the vertebrae into the spinal canal and compress the spinal cord or the spinal nerves with possible serious complications.
It is now being appreciated by surgeons that reinforcing an osteoporotic vertebra with bone cement may lead to fractures of the adjacent vertebra by compression against a very much hardened neighboring vertebra. The other concern is the fact that the bone cement will stay permanently in the vertebra because it is not resorbable. The long term consequence of this is not known, hence, its use is generally avoided in young vertebral fractures.
Treatments of young vertebral fractures are either conservative or surgical. The conservative approach is usually favored when the deformity of the vertebra is not severe and when there is no injury to neural elements. However, the biomechanical alterations caused even by an apparently minor deformity may lead to the development of chronic back pain. Surgical stabilization becomes imperative if there is spinal cord injury, usually associated with significant instability of the spine. The stabilization surgery usually involves massive surgical trauma through either or both anterior and posterior approaches.